Short Explanation about Green Flashes:
Green flashes and green rays above the sun or on a sunset point are optical phenomena. This happens terribly concisely before total sunset and when sunrise. It seems as a inexperienced flash higher than the sun that lasts terribly concisely,mostly only for a few minutes. It's caused by refraction of sun light within the atmosphere.
Also known as a good Sign:
It is suppose as a good luck in some cultures and areas in the World to see the green rays; others see it as a more foreboding omen. Whatever your view point, it is a brief but memorable sight but you have to be quite lucky to see it.
The Green Ray and Green flashes